Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class III. Words Relating to Matter
Section III. Organic Matter
2. Sensation
(3) Taste

397. Sourness.

   NOUN:SOURNESS &c., adj.; acid, acetosity, acerbity, acidity. subacidity; acescence or acescency; acetous fermentation.
  [SOUR ARTICLES] vinegar, acetum, tartar, verjuice, crab, alum; acetic acid; lime, lemon, crab apple, chokeberry, chokecherry; unripe -, green fruit.
   VERB:BE SOUR, turn sour &c. adj.; set the teeth on edge.
  RENDER SOUR &c. adj.; acidify, acidulate, acetify, acetize [are], tartarize, ferment.
   ADJECTIVE:SOUR; acid, acidulous, acidulated; tart, crab, crabbed; acetous, acetose, acerb, acetic; sour as vinegar, sourish; acescent, subacid; hard, rough, unripe, green; astringent, styptic.
   QUOTATION:Every white will have its blacke, And every sweet its soure.—Percy